Chapter 2 • The ESP32 DevKitC Development Board

2.1 Overview

In the last chapter, you had a look at the architecture of the ESP32 processor and its basic features and advantages. You have also read about some of the popular ESP32 development boards available in the marketplace.

Currently, ESP32 DevKitC is one of the most popular development boards based on the ESP32 processor. In this book, all projects to replicate at home or in your lab are based on this development board. It is therefore important that you learn the architecture and the features of this board in detail.

In this chapter, you will be looking at the features of the ESP32 DevKitC development board in greater detail.

2.2 ESP32 DevKitC hardware

The ESP32 DevKitC is a small ESP32 processor-based board developed manufactured by Espressif. As shown in Figure 2.1, the board is breadboard compatible and has the dimensions 55 mm × 27.9 mm. The one used in this book had the marking ESPRESSIF ESP32WROOM-32D on its metal plate.

The board has two connectors located along each side of the board for GPIO, clock, and power line interfaces. Each connector has 19 pins. As shown in Figure 2.2, the two connectors carry the following signals:

The board has a mini USB connector for connection to a PC. The board also receives its power from the USB port. Standard +5 V from the USB port is converted into +3.3 V on the board. In addition, two buttons are provided on the board named EN and BOOT, with the following functions:

EN: This is the Reset button. Pressing this button resets the board.

BOOT: This is the Download button. The board is normally in operation mode where the button is not pressed. Pressing and holding down this button and at the same time pressing the EN button starts the firmware download mode allowing firmware to be downloaded to the processor through the USB serial port.

The pins on the ESP32 DevKitC board have multiple functions. Figure 2.3 shows the functions of each pin. For example, pin 10 is shared with functions GPIO port 26, DAC channel 2, ADC channel 19, RTC channel 7, and RX01.

Note that GPIO34, GPIO35, GPIO36, GPIO37, GPIO38 and GPIO39 ports are input only and cannot be used as output ports (GPIO37 and GPIO38 are not available on the ESP32 board).

The board operates at a typical power supply of +3.3 V although the absolute maximum is specified as +3.6 V. It is recommended that the current capacity of each pin should not exceed 6 mA, although the absolute maximum current capacity is specified as 12 mA. It is therefore important to use current limiting resistors while driving external loads such as LEDs. Depending upon the configuration, the RF power consumption during reception is around 80 mA, and it can be in excess of 200 mA during a transmission.

Programming of the ESP32 DevKitC requires the board to be connected to a PC through its mini USB port. The communication between the board and the PC takes place using the standard serial communication protocol. ESP32 DevKitC is preloaded with firmware that can be used to test the board. This firmware is activated by default when power is applied to the board. Before communicating with this firmware you have to run a terminal emulation program on your PC, such as the HyperTerm, Putty, X-CTU, and others.

Practical Audio DSP Projects with the ESP32

Practical Audio DSP Projects with the ESP32